1. Field of the Invention
The present invention relates to novel peptide derivatives having a nootropic effect and antidementia agent containing the same.
2. Description of Prior Art
Vasopressin has been previously known as a compound having a nootropic effect, i.e., intelligence developing effect. Recently, it has been reported that a peptide seemingly corresponding to a vasopressin fragment, for example, one having the following formula: ##STR2## has such a nootropic effect as that of vasopressin in Science, 221, pp. 1310-1312 (1983).
Further, Brain Research, 371, 17(1986) describes that a peptide having the formula: ##STR3## also has a nootropic effect.